also whats a period graph of function? hows it related to the question?

thanks

A periodic function is one whose values are repeated at regular intervals or periods. On the graph of the function, the period itself is the horizontal distance between two consecutive corresponding points.

If is such that for all values of then is periodic with period . This means that the graph repeats every units horizontally.

To find where , we need to know where the graph crosses the -axis. Between and , the graph cuts the -axis times; so it will cut it another times between and . (That's so far.)

Between and , the graph crosses the -axis just once; so it will cross once between and .